Method of producing electrodes for electric accumulators.



No. 731,308. PATBNTED JUNE 16, 190 3.

E. W. JUNGNER.

METHOD OF PRODUCING ELECTRODES FOR ELECTRIC ACCUMULATORS.

nrmonlon FILED we. 5, 1901.

N0 MODEL. 2 sums-511x521 1.

PATBNTED JUNE 16, 1903.

N0.'73 1,3oa. E. W. JUNGNER. v

G ELECTRODES FOR ELECTRIC AOOUMULATORS.

METHOD OF PRODUGIN APPLICATION FILED AUG. 5, 1901.

2 SHEETS-SHEET 2 no menu.

157111157: llliill'rllrllAlal UNiTED STATES Patented June 16, 1903.

PATENT ERNST WALDEMARJUNGNER, OF STOOKI-IOLM, SWEDEN.

.SPEGIFIGATION forming part of Letters Patent Application filed August 5, 1901 a tappertains ference being ,oxygen combinations e in alkaline solutions.

1 sin that a metallic body p u" an alkaline solution, to

dedf-arsalt whose acid radical forms which 1s ad h-the soluble salt for the purpose y a kind of corrosion a cons a carrier for active masses that ttle'or no conductivity. Such masses usbrought into very close (molecular) twith the conductor, and the electrode this man nor has a very great activity .eferring to the drawings, in which like ,4 parts are similarly designated, Figure 1 is a section of a carrier, showing a carrier the sur- '35--face of which is enlarged. Fig. 2 is a similar howing one Whose surface has been enby electrochemical action. Figs. 3 llustrate the method of carrying out recess.

1c-recesses 5, that are arranged parallel to o another and very close together, the sur- I face of the plate is increased five times. If, however, the recesses are placed farther apart, ":-the surfacewill not'beincreased to such an I extent. Now if the walls of these recesses 5 be similarly provided with cubical recesses 6 the surface of the recesses 5 will be likewise increased five times or that of the original plate 5 or twenty-five times. The walls of these last-mentioned recesses 6 can be similarly enlarged, and theoretically the surface ease of the surface of said mey which it is rendered suitable tack arise,

ceiving and delivering electrical energy.

the surface of a plate be provided with scanned June 16, 1903.

b ,ihcreased until the recesses become ocular-. 1 The recesses of the plate shown Fig. 2have been. made by electrochemicalyme'ans.

,- "'If a metal plate a with a clean smooth surface is used as anode in an electrolyte such that the metal combination formed by electrolysis is' more or less easily soluble, the plate is uniformly attacked at every point; but if, on the other hand, the metal combination formed is substantially insoluble in the electrolyte a coherent layer is immediately formed on the surface of the metal, and the shape of the plate again remains unchanged, as will be the ease of sheet-lead in an electrolyte of concentrated sulfuric acid. In a casewhere the metal combination formed by the electrolyte is soluble with difficulty socalled points of attack are formed at those parts of the surface of the electrode where the density of the current is a maximum,and notches or hollows are provided in the metal M plate around these points, due to the physical or chemical unhomogenous nature of the plate. Within said hollows and simultaneous with their formation new points of ataround which new hollows are formed, and with these last still further hol- 8o lows, and so on until they become almost numberless. Such a structure is shown in Fig. 2. In order to produce this structure, it is therefore necessary that the metal combination formed should not be solublewith such great difficulty as to form a layer, and thus prevent further decomposition of the plate, and, secondly, the metal combination should not be soluble to such a degree that it is dissolved by the electrolyte as soon as formed. Consequently it is only necessary that the formation of the metal combination be more rapid than the solution thereof in the electrolyte. The distances between the points of attack on the surface of the plate, as Well as the depth of the hollow, depend in addition to the nature of the plate, metal, and the electrolyte on the density of the current, the degree of concentration, and the temperature of the electrolyte, as well as on the physical 1.0 structure and shape of the surface of the electrode, the distance of the cathode, the.

In order to effect as uniform an enlargement of the surface of the metal plate to act as an manner described above.

electrode carrier, I place such plate a as anode in a suitable vessel 7 and opposite to it place a cathode is, that is provided with points 8 equidistant from one another and also equidistant from the plate to be treated. The whole cathode h, Fig. 3, is covered with a neutral and electrically non-cond uctivema- Ieri'al h, excepting at the'points 8. The points of attack on the surface of the anode a arise in this case at those places that are opposite the points 8 of cathode kl Fig. 4 shows another method of procedure. In this case the anode a is covered with anonconductive material h,- flnthis cover aresmall circular holes 71, atguniform distances;

apart, through which the surface of-the' anode a will be exposed to the action of th'eele'ctrolyte and current. As soon as the hollows have reached a certain depth the cover'canv be removed. The points of attack can be arranged so close together that they form, so to speak, lines of attack. In Fig. 3 the points may be replaced by sharply-pointed projections, straight or curved; but they of course will be insulated up to their edges. These arrangements are in many cases unnecessary, since a uniform hollowing can be obtained by simply roughening the surface with a file or emery-paper, whereby small elevations are produced that form points of attack. The metal combination that has not been dissolved and remains in the hollows may sometimes be used directly as an active mass in a suitable electrolyte and serve to accommodate or supply electrical energy. If the metal combination is not to be used as an active mass, it can be removed from the metal plate by putting the latter into a solution adapted to dissolve it, but not to dissolve the metal itself. Suitable substances can then be pressed or melted and run into the hollows of the metal plate. Plates of all metals that are indifferent in alkali can be treated in the Owing to the various circumstances which come into consideration it is necessary to make experiments for each particular case in order to ascertain the most suitable density and size of the hollows with reference to the thickness of the metal plate. Said hollows should in this respect be such that they can be seen with the naked eye, or at least with a weak magnifying-glass. At least the first or largest hollows should be such as to be discerned with the naked eye.

As practical employment of the method described above the following special case may be mentioned: If a plate of pure nickel is placed as anode in a solution of chlorid of sodium, soluble chlorid of nickel is formed and the surface is uniformly attacked at all points, by which no appreciable enlargement of the surface takes place. If the same be also placed as an anode in a concentrated solution of an alkali-metal hydrate, a thin layer of oxid of nickel is formed on the surface of the plate, the said combination being insoluble in alkali, and thus protecting the plate against further effect. If, on the other hand, the solution of chlorid of sodium and alkali are mixed in certain proportions, according to the density of current, temperature, &c., oxychlorids of nickel of various compositionfor instance, as stated in the formula beloware formed on the surface of the nickel plate, (especially if the said surface has 'previouslybeen rubbed with a fine emery-paper or the like.)

i The oxychlorids or nickel are soluble in the "electrolyte with difficulty and form on the surface of the electrode a green or greenish-blalcklayenwhich can be made very hard andicompact by suitable means and which adheresfirmlYto the metal. If the electrode now is placed as anode in a twenty to thirty percentpalka-line, solution from six to eight hours and withaacu'rrent of about one ampere persqn'are: cime'ter, the layer of oxychlorid of nickelgvnextto'the metal will be transformed 'by aridtbyri'nto a; high oxygen compound of nickel. -fI f the layer formed on a nickel plate treated i'-,n'- this'. manner is removed, which can be efi ectemrfor instance, by quickly plung'i-ngtitheiplate;into hydrochloric acid, 3

QH iot+ sto+qai so that the surface is'inetallicallypnre, its greatest porosity can be distinctly see If the said plate is then amalgamated:inasuitable manner-for instance, b'y nfanspf a zinc amalgam in diluted hyd :ocltlor" i}cacid and placed as a cathode inabol-utihri of-alkali zincate, it is capable of receiving acousiderable quantity of zinc, which ivillfiad here thereto. .C-onsequently the said? plate".

can be advantageously used as the. electrode;

in a bath of such solution.

In the same manner as described-"above with reference to nickel plates other-metals can be prepared, so that they can by enlargement of the surface be used as a support for.

the active mass in electric accumulators with an alkaline electrolyte. cially the case with copper, cadmium, iron, however with suitable modificat and changes with reference to the nat concentration, and temperature of the trolytic bath, the density of current,

Iron and copper can be treated as anodes-in This is espesuitable transformation as an active mass on the iron support in alkaline electrolytes.

The invention can be used in accumulators with unchan geable electrolyte, especiallywith combinations of silver, nickel, copper, cadmium, and iron.

Having thus described my said invention,

what I claim as new therein, and desire to secure by Letters Patent, is-- 1. The method of electrolytically increasing the surface of carriers for active masses of accumulator-electrodes that are chemically indifferent to alkaline solutions, which consists in placing a cathode and a plate of a suitable metal, as anode, into a solution of an alkali-metal hydrate containing a suitable salt capable of forming a soluble combination with said metal plate, said combinationbein g soluble in the solution with less rapidity than it is formed, and passing an electric current, substantially as described. r

2. The method of making carriers for active masses of accumulator-electrodes'that are chemically indifferent to alkaline solutions, which consists in placing'a cathode and a plate of a suitable metal, having a roughened surface, into a solution of an alkali-metal hydrate containing a salt capable of forming a soluble combination with said metal, the said combination being soluble in the solutionwith less rapidity than it is formed, and passingan electric current, substantially as described.

3. The method of making carriers for active masses of accumulator-electrodes that are chemically indifferent to alkaline solutions, which consists in placing a suitable cathode and a suitable metal plate as anode in a solution of an alkali-metal hydrate containing alkali-metal chlorid and passing a current of electricity, substantially as described.

4. The method of making carriers for active masses of accumulator-electrodes that are chemically indifferent to alkaline solutions, which consists in placing a cathode having regularly-disposed conducting-points opposite a plate of a suitable metal as anode in a solution of an alkali-metal hydrate containing a salt capable of forming a combination with said metal that is soluble in the said solution with less rapidity than the for mation of the said salt, substantially as described.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

ERNST WALDEMAR J UN GNER.

Witnesses:

TH. BOOK, E. O. ERIOSON. 

